1. Field of the Invention
This invention relates generally to network switching devices and more particularly to Fibre Channel switching devices.
2. Description of the Related Art
The Fibre Channel family of standards (developed by the American National Standards Institute (ANSI)) defines a high speed communications interface for the transfer of large amounts of data between a variety of hardware systems such as personal computers, workstations, mainframes, supercomputers, storage devices and servers that have Fibre Channel interfaces. Use of Fibre Channel is proliferating in client/server applications which demand high bandwidth and low latency I/O such as mass storage, medical and scientific imaging, multimedia communication, transaction processing, distributed computing and distributed database processing applications.
Fibre Channel offers advantages over traditional channel and network technology. Conventional channel technology (e.g., telephony) provides a point-to-point connection (or service) form one device to another. Conventional channels deliver data with high speed and low latency. Channels, however, are not suited for providing connectivity among many clients and are not suited for small-packet bursty traffic. Conventional networks provide shared access to bandwidth and are designed to handle unpredictable and bursty traffic. Networks, however, are software intensive and are not able to meet the growing bandwidth requirements of many client/server applications.
Fibre Channel is an alternative to conventional channel and network connectivity technologies and is used to deliver high speed and low latency connectivity among many clients. Fibre channel establishes logical point-to-point connectivity from a source device node (port) to a destination device node (port) (a logical port-to-port serial channel). The logical port-to-port serial channel is used to transfer data from a source device (node) to a destination device node. Each node (source and destination) has a buffer (either a send buffer or a receive buffer) and data transfer is effected by moving data from the send buffer at the source node to a receive buffer at the destination node. Because the transfer scheme is logically point-to-point (node-to-node) there is no need for Fibre Channel to handle various network protocols. With Fibre Channel, data is moved from one node to another without regard to data format or meaning.
Fibre Channel uses one of several topologies (e.g., a point to point topology, a fabric topology, or a loop topology) to establish a logical point-to-point serial channel. The Fibre Channel point to point topology connects two Fibre Channel systems directly. The Fibre Channel loop topology is an arbitrated loop with ring connections that provide arbitrated access to shared bandwidth. The Fibre Channel fabric topology uses a switching fabric built from one or more Fibre Channel switches to provide a bidirectional connection from one node to another. With the fabric topology, each Fibre Channel node (device) manages only a simple point-to-point connection between itself and the fabric and the fabric manages and effects the connection between the nodes. Each transmitting node (port) enters the address of a destination node (port) in a frame header and the fabric establishes the connection.
Conventional switching systems and methods are not suited for the high bandwidth and low latency requirements of Fibre Channel. Thus, there is a need for an improved switching system and method.